There is a strong consumer demand for bio-based candles as an environmentally friendly alternative to petroleum-based paraffin candles. Soy candles that are produced from derivatized soybean oil were reported to burn longer and to produce less soot, carbon dioxide, and potentially harmful organic volatiles. Scented soy candles better distribute aromas due to their lower melting point, as compared with the paraffin wax products.
The following four major components are known to be used for making bio-based candles from renewable feedstock:
1. Partially and fully hydrogenated vegetable oils (primarily soybean oil);
2. Fatty acids (primarily palmitic and stearic acids);
3. Polyol fatty acid partial esters (such as glycerin mono- and di-stearate); or
4. Products of catalytic trans-esterification of 1 and 3, above.
Many candle compositions optionally contain colorants, fragrances, insect repellants, antioxidants, and/or UV-stabilizers/color stabilizers.
Epoxides of hydrogenated natural oils and their derivatives were reportedly used as intermediates for preparation of candle formulation components.
U.S. Pat. No. 6,063,144 covers candle compositions of vegetable oil, stearic acid, hydrogenated castor oil, and vegetable-derived wax (such as candelilla wax).
U.S. Pat. No. 6,214,918 covers candle compositions of paraffin wax, soybean oil, and a branched hydrocarbon compatibilizer/binding agent.
U.S. Pat. Nos. 6,284,007 and 6,497,735 cover candle compositions of petroleum wax and vegetable lipid components. The vegetable lipid components include vegetable oil or fatty acid/vegetable oil mixtures.
U.S. Pat. No. 6,503,285 and U.S. Publication No. 2005/0060927 cover candle compositions of Partially Hydrogenated Vegetable Oils (PHVO) and Polyol Fatty Acid Partial Esters (PFAPE), such as fatty acid monoesters of glycerol and/or sorbitan.
U.S. Pat. No. 6,599,334 and U.S. Publication No. 2007/0282000 cover candle compositions of PHVO. The composition also contains small amounts of synthetic wax, such as poly-alpha-olefins, and a second hydrogenated vegetable or petroleum oil.
U.S. Pat. No. 6,645,261 covers candle compositions of PHVO of several different solid fat index with different degrees of hydrogenation and palmitic acid.
U.S. Pat. No. 6,730,137 covers candle compositions of paraffin wax and PHVO having a low free fatty acid content.
U.S. Pat. No. 6,770,104 covers candle compositions of PHVO, Fully Hydrogenated Vegetable Oil (FHVO) and PFAPE having a low free acid content.
U.S. Pat. No. 6,773,469 covers candle compositions of PHVO, PFAPE, and fatty acids such as palmitic acid
U.S. Pat. No. 6,773,548 covers candle compositions of PHVO, stearic acid, and a creamy vegetable liquid shortening.
U.S. Pat. No. 6,797,020 covers candle compositions of FHVO and several PHVO of varies degrees of hydrogenation in combinations with PFAPE having a low fatty acid content.
U.S. Pat. Nos. 6,824,572 and 7,217,301 cover candle compositions of PHVO and fatty acids, such as palmitic and stearic acids.
U.S. Pat. No. 7,128,766 covers candle compositions of FHVO and PHVO, which includes both soy and palm oil in the same formulation. Paraffin wax, beewax, or carnauba wax is added optionally. Poly-alpha-olefins and glycerin mono-stearate are used as compatibilizers.
U.S. Pat. No. 7,192,457 covers candle compositions of products of catalytic trans-esterification of vegetable oils, FHVO, and PHVO having a low free acid content.
U.S. Publication No. 2003/0046860 covers candle compositions of FHVO, PHVO, fatty acids, and esters of fatty acids that include PFAPE (monoglycerides an diglycerides), canola methyl esters, propylene glycol monoesters, sorbitan tristearate, and mixtures thereof.
U.S. Publication No. 2003/0061760 covers candle compositions of FHVO, PHVO, stearic acid, a plant-derived surfactant, and microcrystalline petroleum/paraffin wax.
U.S. Publication No. 2004/0200136 covers candle compositions of PHVO, stearic acid, a plant-derived surfactant, petroleum, and natural waxes.
U.S. Publication. No. 2004/0250464 covers liquid candle compositions of PHVO and hardening agent selected from the group consisting of fatty acids, stearin, cetyl alcohol, arachidyl alcohol, and myricyl alcohol and their mixtures.
U.S. Publication No. 2006/0042157 covers candle compositions of PHVO, shea butter, and vegetable oil, such as olive oil.
U.S. Publication No. 2006/0272200 covers candle compositions of PHVO, trans-esterified PHVO, PFAPE, such as mono- and diglycerides, trans-esterified PFAPE, such as mono- and diglycerides. The composition may also contain mineral wax and insect wax.
U.S. Publication No. 2007/0039237 covers candle compositions of PHVO having a blend of soy and palm, PFAPE, and other waxes, such as beewax, carnauba wax, petroleum wax, and Montana wax, used as migration inhibitors.
The following two references contain information on preparation and the use of epoxy-derivatives of hydrogenated vegetable oils as intermediates for obtaining candle formulation components:
U.S. Publication No. 2007/0151480 covers compositions of at least one hydrogenated and partially hydrogenated heat bodied (polymerized; 230° C. and 200-300 psi) hydrogenated oil. The hydrogenated polymer may contain at least one epoxy-group that is formed as a result of oxidative curing. The epoxy-group may be converted into hydroxyl functional group due to hydrolysis. Th process is very energy-intensive.
The '480 publication includes varies types of binders and coatings as well as candle wax (all examples are based on linseed oil) that may optionally contain a vegetable oil, an alkyl ester (propylene glycol mono-stearate, mono- or diglycerides etc.) or petroleum derivative (paraffin, microcrystalline wax, mineral oil), and their combinations.
U.S. Publication No. 2008/0281115 covers compositions of chemically modified PHVO. The modification process includes three-step process that includes a) epoxidation, b) ring-opening through acid-catalyzed hydrolysis to convert the epoxide into the hydroxylate, and c) esterification of the hydroxyl-groups with the use of fatty acid anhydride using butyril anhydride in the methylene chloride solvent. It was specifically mentioned that the epoxy intermediate did not have significantly altered thermal properties compared to PHVO. The multi-step process is very complex.
The entire contents and disclosure of these references are incorporated herein by reference.
Notwithstanding the above literature, the need remains for bio-based wax composition suitable for candle preparations.